Hong Kong's colourful annual gay pride parade took on an overtly political tinge yesterday as Occupy moved in, boosting numbers and adding umbrellas as well as a dose of controversy.

Thousands marched through the rain from Victoria Park to Tamar Park to demand legislation outlawing discrimination on the grounds of sexual orientation. While organisers had ordered 500 rainbow umbrellas before they became a protest symbol, many more were on show, perhaps due to the Occupy factor or maybe because of the rain.

Federation of Students leaders Alex Chow Yong-kang and Lester Shum, two key figures in the Occupy protests, took part and backed the call for equal rights for gays. "Regardless of whether you are gay, bisexual or transgender, we all have the moral responsibility to speak out. Stand up to change the world. Confront unreasonable pride, prejudice, cruelty and indifference," Chow, the federation's secretary general, told the crowd. Organisers said 8,900 took part, up from their estimate of 5,200 last year. Police said 4,700 people attended at the peak of the march, compared with 4,500 last year.

Parade spokeswoman Alice Wei Siu-lik said "umbrella movement" students had boosted the turnout. Three hundred people had signed up as volunteers for the rally, about half of whom were students, she said. More corporate sponsorship was another factor helping with publicity, she said, and the MTR Corp had allowed organisers to display adverts at all stations at a discount rate for a month.

The move to link the democracy and gay-rights movements was not universally welcomed.

"It is inappropriate to bundle a gay movement with a movement for democracy and freedom," the Family School Sexual Orientation Discrimination Ordinance Concern Group - an anti-gay-rights group headed by Roger Wong Wai-ming, the father of Scholarism convenor Joshua Wong Chi-fung - said. "In our understanding, the so-called demands made in the 'equal rights movement for the gay' are contravening human rights and justice."

When asked to respond to his father's remarks, Joshua Wong said he was "too busy" to comment.

A spokesman for the Constitutional and Mainland Affairs Bureau said society was "still deeply divided as to whether legislation should be enacted to prohibit discrimination on grounds of sexual orientation or gender identity. Some are in support from the perspective of equal opportunity, while others are concerned that this may deal a blow to family, religion and education. This is a highly controversial and sensitive issue in Hong Kong which must be tackled cautiously."

Commission chairman Dr York Chow Yat-ngok joined the parade for the second time, despite criticism from anti-gay groups last year.